Lens driving mechanism and method for controlling the same

ABSTRACT

A lens driving mechanism is provided. The lens driving mechanism is configured to drive an optical lens, including a holder, a base, a first elastic element, and a first biasing element. The optical lens is disposed in a receiving space of the holder. The base has a central axis, and the holder is movable relative to the base. The first elastic element is connected to the holder and the base. The first biasing element exerts a force on the holder so that an optical axis of the optical lens has an angular displacement relative to the central axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/316,845, filed Apr. 1, 2016, and Taiwan Patent Application No.106102854, filed Jan. 25, 2017, the entirety of which are incorporatedby reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The application relates in general to a lens driving mechanism, and inparticular to a lens driving mechanism having a biasing element.

Description of the Related Art

Thanks to ongoing technological development, recent electronic devices(such as tablet computers and smartphones) usually include a lens modulecapable of aiding in photography or recording video. However, an imagemay come out blurry if the user shakes the lens module in the electronicdevice. To increase image quality, it is increasingly important todesign a shockproof lens module.

BRIEF SUMMARY OF INVENTION

To address the deficiencies of conventional products, an embodiment ofthe invention provides a lens driving mechanism, configured to move anoptical lens, including a holder, a base, a first elastic element, and afirst biasing element. The optical lens is disposed in a receiving spaceof the holder. The base has a central axis, and the holder is movablerelative to the base. The first elastic element is connected to theholder and the base. The first biasing element exerts a force on theholder so that an optical axis of the optical lens has an angulardisplacement relative to the central axis.

In some embodiments, the first biasing element is made of a shape-memoryalloy material.

In some embodiments, the lens driving mechanism further comprises aconductor formed on the base by insert molding or 3D molded interconnectdevice technology, wherein the conductor is electrically connected tothe first biasing element.

In some embodiments, the first biasing element has a first section and aU-shaped second section, and the first section is substantially parallelto the central axis and connects to the second section.

In some embodiments, the first biasing further has a third sectionsubstantially perpendicular to the central axis, and the second sectionconnects to the first section and the third section.

In some embodiments, the second section and the third section arelocated on opposite sides of the first section.

In some embodiments, the base has a main body and at least oneprotrusion, the protrusion protrudes toward the holder from the mainbody, and the first elastic element connects to the protrusion and theholder.

In some embodiments, the lens driving mechanism further comprises asecond biasing element and a plate, the second biasing element connectsto the base and the plate, and the second biasing element forces thebase and the holder to move relative to the plate.

In some embodiments, the second biasing element forces the base and theholder to move relative to the plate in a direction that issubstantially perpendicular to the central axis.

In some embodiments, the second biasing element is made of ashape-memory alloy material.

In some embodiments, the first biasing element and the second biasingelement are situated in different positions along the central axis.

In some embodiments, the lens driving mechanism further comprises arolling element disposed between the base and the plate.

In some embodiments, the lens driving mechanism further comprises asecond elastic element connected to the base and the plate.

In some embodiments, the lens driving mechanism further comprises animage sensor affixed to the base.

In some embodiments, the base is between the holder and the plate, andthe image sensor is between the base and the plate.

An embodiment of the invention provides a method for controlling thelens driving mechanism, wherein the lens driving mechanism furthercomprises a plurality of first biasing elements disposed on differentsides of the base, the method comprising: applying a plurality ofdriving signals to the respective first biasing elements to move theholder along the central axis relative to the base.

Another embodiment of the invention provides a method for controllingthe lens driving mechanism, wherein the lens driving mechanism furthercomprises a plurality of first biasing elements disposed on differentsides of the base, the method comprising: applying a plurality ofdriving signals to the respective first biasing elements so that theoptical axis has an angular displacement relative to the central axis.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a schematic diagram of a lens driving mechanism according toan embodiment of the invention;

FIG. 2 is an exploded diagram of the lens driving mechanism in FIG. 1;

FIG. 3 is a schematic diagram of the lens driving mechanism with thehousing in FIG. 1 omitted therefrom;

FIG. 4 is a schematic diagram of the holder moving in the direction ofthe optical axis;

FIG. 5 is a schematic diagram of the optical axis having an angulardisplacement relative to the central axis;

FIG. 6 is a schematic diagram of a lens driving mechanism according toanother embodiment of the invention;

FIG. 7 is an exploded diagram of the lens driving mechanism in FIG. 6;

FIG. 8 is a schematic diagram of the lens driving mechanism with thehousing in FIG. 6 omitted therefrom;

FIG. 9 is a top plan view of the plate, the second elastic elements, thesecond biasing elements, and the rolling elements in FIG. 8; and

FIG. 10 is a schematic diagram of a lens driving mechanism according toanother embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

The making and using of the embodiments of the lens driving mechanismsare discussed in detail below. It should be appreciated, however, thatthe embodiments provide many applicable inventive concepts that can beembodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the embodiments, and do not limit the scope of the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. It should be appreciated thateach term, which is defined in a commonly used dictionary, should beinterpreted as having a meaning conforming to the relative skills andthe background or the context of the present disclosure, and should notbe interpreted by an idealized or overly formal manner unless definedotherwise.

Referring to FIGS. 1-2, FIG. 1 is a schematic diagram of a lens drivingmechanism 1 according to an embodiment of the invention, and FIG. 2 isan exploded diagram of the lens driving mechanism 1 in FIG. 1. The lensdriving mechanism 1 can be disposed in an electronic device, such as acamera, a tablet computer, or a cell phone, and it can be configuredwith an optical lens (not shown) disposed therein. The optical lens ismovable relative to an image sensor of the electronic device, so thatthe lens driving mechanism 1 has an auto-focusing function.

As shown in FIGS. 1-2, the lens driving mechanism 1 primarily comprisesa base 10, a holder 20 made of an insulation material, a housing 30, aplurality of first elastic elements S1 to S4, a plurality of firstbiasing elements W1 to W4, and a plurality of positioning members P1 andP2. A receiving space 20R is extended through the holder 20, so that anoptical lens (not shown) can be disposed therein. An image sensor (notshown) is disposed under the base 10 and configured to receive lightfrom the outside of the lens driving mechanism 1 and through the opticallens. The base 10 has a central axis C which coincides with an opticalaxis O of the optical lens. The base 10 has a main body 11 formed as asquare or rectangular structure and four protrusions 12. The protrusions12 are respectively disposed at the four corners of the main body 11 andprotrude from the main body 11 toward the holder 20. As shown in FIG. 3,the holder 20 is disposed on the base 10 and connects to the fourprotrusions 12 of the base 10 by the four first elastic elements S1 toS4 (such as metal springs).

The first biasing elements W1 to W4 connect to the base 10 and theholder 20. The first biasing elements W1 to W4 may be made of ashape-memory alloy (SMA) material, and their lengths can be changed byapplying one or more driving signals (e.g., electrical current) to themfrom an external power source. For example, when applying a drivingsignal to heat the first biasing elements W1 to W4, the first biasingelements W1 to W4 are defoiiiied (e.g., elongated or shortened). Whenthe application of the driving signal is stopped, the deformed firstbiasing elements W1 to W4 will recover to their original lengths. Inother words, by applying an appropriate driving signal, the lengths ofthe first biasing elements W1 to W4 can be controlled to alter theposture of the holder 20. The first biasing elements W1 to W4, forexample, may be made of a titanium-nickel (TiNi) alloy, atitanium-palladium (TiPd) alloy, a titanium-nickel (TiNiCu) alloy, atitanium-nickel-palladium (TiNiPd) alloy, or a combination thereof.

Referring to FIGS. 2-3, FIG. 3 is a schematic diagram of the lensdriving mechanism 1 in FIG. 1, in which the housing 30 is omitted. Asdescribed above, the holder 20 connects to the four protrusions 12 ofthe base 10 through the four first elastic elements Si to S4,respectively, and the first biasing elements W1 to W4 are respectivelydisposed on the four different sides of the body 11 and connect to theholder 20 and the base 10. Specifically, the two ends of each of thefirst biasing elements W1 to W4 are electrically connected to twoconductive blocks L, respectively, and the conductive blocks L arerespectively affixed to the holder 20 and the base 10 (for example, theyare affixed to the holder 20 and the base 10 by an engaging means or anadhesive). The first biasing elements W1 to W4 may be electricallyconnected to the corresponding first elastic elements Si to S4 throughthe respective conductive blocks L.

Referring to FIG. 3, the lens driving mechanism 1 further comprises aplurality of electric conductors E (such as conductive wires) which areformed on the base 10 by insert molding or 3D molded interconnect device(MID) technology. The conductors E electrically connect to the firstelastic elements Si to S4 and the first biasing elements W1 to W4 toform four independent circuits, respectively, whereby driving signals(e.g., current) can be supplied to them from an external power source,and the lengths of the first biasing elements W1 to W4 can be changed toadjust the posture of the holder 20. It should be noted that, since theconductors E are formed on the base 10 by insert molding or 3D moldedinterconnect device technology, the number of components of the lensdriving mechanism 1 can be reduced and the dimensions thereof can begreatly reduced. In addition, since the first elastic elements S1 to S4are electrically conductive (such as springs made of metal), the firstbiasing elements W1 to W4 and the conductors E can be electricallyconnected to each other, so that no additional wires are required in thelens driving mechanism 1, saving space.

It should be understood that each of the first biasing elements W1 to W4is electrically independent and connects to an external power source.Thus, a plurality of different driving signals can be respectivelysupplied to the first biasing elements W1 to W4 by the external powersource, and the first biasing elements W1 to W4 can be independentlycontrolled to have different or the same length variations. For example,when applying driving signals to the first biasing elements W1 to W4,the first biasing elements W1 to W4 are deformed, so that the firstbiasing elements W1 to W4 can force the holder 20 and the optical lensto move along the optical axis O relative to the base 10, or force theoptical axis O to have an angular displacement relative to the centralaxis C of the base 10, to achieve the function of fast optical focus oroptical image stabilization (OIS).

Still referring to FIG. 3, two columnar position members P1 and P2 aredisposed on each side of the main body 11 of the base 10. The firstbiasing elements W1 to W4 are in contact with and extended around theposition members P 1 and P2. All the first biasing elements W1 to W4 canbe divided into three sections: a first section W11, a second sectionW12, and a third section W13. The first section W11 is substantiallyparallel to the central axis C, and the second section W12 has aU-shaped structure and connects to the first section W11. The thirdsection W13 is substantially perpendicular to the central axis C,wherein the second section W12 is connected to the first section W11 andthe third section W13, and the second section W12 and the third sectionW13 are respectively located on the left and right sides of the firstsection W11. As the first biasing elements W1 to W4 extend around theposition members P1 and P2 to form the three sections W11, W12, and W13,the lengths of the first biasing elements W1 to W4 disposed on each sideof the main body 11 can be increased. Therefore, when the first biasingelements W1 to W4 are deformed, more variation in length can begenerated. Furthermore, due to the distance between the position membersP1 and P2 in the direction of the central axis C, short-circuits betweenthe first, second, and third sections W11, W12, and W13 can be avoided.

How the holder 20 and the optical lens are moved relative to the base 10by controlling the length variations of the first biasing elements W1 toW4 will be described in detail below. In the present embodiment, asshown in FIG. 4, when the driving signals are applied to the firstbiasing elements W1 to W4 on the four sides of the body 11, if thelength variations thereof are substantially the same, the first biasingelements W1 to W4 can force the holder 20 and the optical lens to moverelative to the base 10 in the direction of the optical axis O.

On the other hand, when different driving signals are applied to thefirst biasing elements W1 to W4 and the length variations thereof aredifferent from each other, the holder 20 and the optical axis O of theoptical lens can have an angular displacement θ relative to the centralaxis C of the base 10 (as shown in FIG. 5).

That is, by independently applying different driving signals to thefirst biasing elements W1 to W4, the length variations thereof canrespectively be controlled, so that the holder 20 and the optical lenscan be moved relative to the base 10 along the optical axis O, or theoptical axis O can have an angular displacement θ relative to thecentral axis C of the base 10, so as to facilitate auto-focusing andoptical image stabilization of the lens driving mechanism 1.Furthermore, in another embodiment, the lens driving mechanism 1 mayhave only one first elastic element S1 and one first biasing element W1,to form a circuit loop with the conductor E and the external powersource. When a driving signal is applied to the first biasing elementW1, the first biasing element W1 is deformed, and the optical axis O canbe angularly shifted by an angular displacement θ relative to thecentral axis C of the base 10, so that tilt angle compensation of thelens driving mechanism 1 can be accomplished.

According to the aforementioned embodiment, a control method of the lensdriving mechanism 1 further is provided, comprising: applying aplurality of driving signals to the first biasing elements W1 to W4 suchthat the holder 20 and the optical lens move in the direction of theoptical axis O. Alternatively, a plurality of driving signals may beapplied to the first biasing elements W1 to W4 such that the opticalaxis O of the optical lens has an angular displacement θ relative to thecentral axis C of the base 10.

FIGS. 6-7 are schematic and exploded diagrams of a lens drivingmechanism 2 according to another embodiment of the invention. The maindifference between the lens driving mechanism 2 in the presentembodiment and the lens driving mechanism 1 in the aforementionedembodiment is that the lens driving mechanism 2 further comprises aplate 40, a plurality of second elastic elements SR1 and SR2, aplurality of second biasing elements WR1 to WR4, and a plurality ofrolling elements B, wherein the same elements corresponding to theaforementioned embodiment (FIGS. 1-5) are not described again here indetail.

Referring to FIGS. 7-9, an image sensor (not shown) is disposed on theplate 40, the base 10 is disposed on the plate 40, and the secondelastic elements SR1 and SR2 and the second biasing elements WR1 to WR4are connected to the plate 40 and the base 10. Specifically, the twoends of the second elastic elements SR1 and SR2 connect to the plate 40and the base 10, respectively, and the two ends of the second biasingelements WR1 to WR4 connect to the plate 40 and the base 10 via theconductive blocks L (as shown in FIGS. 8-9), wherein the second biasingelements WR1 to WR4 and the first biasing elements W1 to W4 are locatedin different positions in the direction of the central axis C conductorsE. When an external power source applies different driving signals tothe second biasing elements WR1 to WR4, the second biasing elements WR1to WR4 can deform and force the base 10 and the holder 20 to moverelative to the plate 40 in a direction that is substantiallyperpendicular to the central axis C. Therefore, the displacement betweenthe optical axis O and the central axis C due to shaking of the lensdriving mechanism 2 in the horizontal direction can be compensated for.

It should be noted that the rolling elements B of the lens drivingmechanism 2, such as balls or rollers, are sandwiched between the plate40 and the base 10. When the second biasing elements WR1 to WR4 areexpanded or contracted to force the base 10 and the holder 20 to moverelative to the plate 40, the base 10 and the holder 20 can be guided tomove in the horizontal direction guided by the rolling elements B. Thus,damage to the mechanism due to contact between the plate 40 and the base10 can be efficiently prevented.

FIG. 10 is schematic diagram of a lens driving mechanism 3 according toanother embodiment of the invention. The main difference between thelens driving mechanism 3 in the present embodiment and the lens drivingmechanism 2 in the aforementioned embodiment is that the plate 40′ inthe lens driving mechanism 3 does not have any receiving space forreceiving the image sensor. The plate 40′ is affixed to a casing of anelectronic device, and an image sensor IM is affixed to a rear surface101 of the base 10. Here, the base 10 is between the holder 20 and theplate 40′, and the image sensor IM is between the base 10 and the plate40′. Thus, when the second biasing elements WR1 to WR4 deform, thesecond biasing elements WR1 to WR4 can force the base 10, the holder 20,and the image sensor IM to move together in a direction that issubstantially perpendicular to the central axis C. In other words, theimage sensor IM and the optical lens disposed in the holder 20 can movetogether relative to the plate 40′, so that vibration compensation ofthe lens driving mechanism 2 can be achieved.

In summary, a lens driving mechanism and a control method thereof areprovided. The lens driving mechanism is configured to drive an opticallens, primarily comprising a holder, a base, at least one first elasticelement, and at least one first biasing element. The first elasticelement connects to the holder and the base. The first biasing elementalso connects to the holder and the base. When the length variation ofthe first biasing element occurs, the holder and the optical lens willmove or have an angular displacement relative to the central axis of thebase. Therefore, the functions of optical focus or optical shakingcompensation can be accomplished.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having the same name (but for use of the ordinalterm) to distinguish the claim elements.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention. It isintended that the standard and examples be considered as exemplary only,with a true scope of the disclosed embodiments being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A lens driving mechanism, configured to move anoptical lens, comprising: a base, having a central axis; a holder,configured to hold the optical lens, wherein the holder is movablerelative to the base; a first elastic element, connected to the holderand the base; and a first biasing element, connected to the holder andthe base, wherein the first biasing element forces the holder and theoptical lens to move relative to the base, and an optical axis of theoptical lens has an angular displacement relative to the central axis.2. The lens driving mechanism as claimed in claim 1, wherein the firstbiasing element is made of a shape-memory alloy material.
 3. The lensdriving mechanism as claimed in claim 1, further comprising a conductorformed on the base by insert molding or 3D molded interconnect devicetechnology, wherein the conductor is electrically connected to the firstbiasing element.
 4. The lens driving mechanism as claimed in claim 1,wherein the first biasing element has a first section and a U-shapedsecond section, and the first section is substantially parallel to thecentral axis and connects to the second section.
 5. The lens drivingmechanism as claimed in claim 4, wherein the first biasing further has athird section substantially perpendicular to the central axis, and thesecond section connects to the first section and the third section. 6.The lens driving mechanism as claimed in claim 5, wherein the secondsection and the third section are located on opposite sides of the firstsection.
 7. The lens driving mechanism as claimed in claim 1, whereinthe base has a main body and at least one protrusion, the protrusionprotrudes toward the holder from the main body, and the first elasticelement connects to the protrusion and the holder.
 8. The lens drivingmechanism as claimed in claim 1, wherein the lens driving mechanismfurther comprises a second biasing element and a plate, the secondbiasing element connects to the base and the plate, and the secondbiasing element forces the base and the holder to move relative to theplate.
 9. The lens driving mechanism as claimed in claim 8, wherein thesecond biasing element forces the base and the holder to move relativeto the plate in a direction that is substantially perpendicular to thecentral axis.
 10. The lens driving mechanism as claimed in claim 8,wherein the second biasing element is made of a shape-memory alloymaterial.
 11. The lens driving mechanism as claimed in claim 8, whereinthe first biasing element and the second biasing element are situated indifferent positions along the central axis.
 12. The lens drivingmechanism as claimed in claim 8, wherein the lens driving mechanismfurther comprises a rolling element disposed between the base and theplate.
 13. The lens driving mechanism as claimed in claim 8, furthercomprising a second elastic element connected to the base and the plate.14. The lens driving mechanism as claimed in claim 8, wherein the lensdriving mechanism further comprises an image sensor affixed to the base.15. The lens driving mechanism as claimed in claim 14, wherein the baseis between the holder and the plate, and the image sensor is between thebase and the plate.
 16. A method for controlling the lens drivingmechanism as claimed in claim 1, wherein the lens driving mechanismfurther comprises a plurality of first biasing elements disposed ondifferent sides of the base, the method comprising: applying a pluralityof driving signals to the respective first biasing elements to move theholder along the central axis relative to the base.
 17. A method forcontrolling the lens driving mechanism as claimed in claim 1, whereinthe lens driving mechanism further comprises a plurality of firstbiasing elements disposed on different sides of the base, the methodcomprising: applying a plurality of driving signals to the respectivefirst biasing elements so that the optical axis has an angulardisplacement relative to the central axis.